Senior Israeli security officials told the magazine that the Mossad has been ratcheting down by “dozens of percent” in recent months secret efforts to disable or delay the Islamic Republic’s nuclear program.

The reduction runs across a wide spectrum of operations, the officials said, and includes cutting back not only alleged high-profile missions such as assassinations and detonations at Iranian missile bases, but also efforts to gather firsthand on-the-ground intelligence and recruit spies inside the Iranian program.

One official told TIME the new hesitancy to operate in Iran has caused “increasing dissatisfaction” inside the Mossad. Another senior security officer attributed the reluctance to Prime Minister Binyamin Netanyahu, saying the Prime Minister is worried about the consequences of a covert operation being discovered or going awry.

Iranian intelligence already has cracked one cell trained and equipped by Mossad, Western intelligence officials confirmed to TIME. The officials admitted that the detailed confession on Iranian state television last year by Majid Jamali Fashid for the January 2010 assassination by motorcycle bomb of nuclear scientist Massoud Ali Mohmmadi was genuine.

The report also noted that the covert campaign also invites retribution from Iran’s own far-reaching underground, which may be a reason for Israel scaling it back. TIME noted the recently thwarted plots against Israeli targets in Thailand, Azerbaijan, Singapore and Georgia, as well as the attack near the Israeli embassy in New Delhi, which Indian officials have blamed on Iran.

While scaling back covert operations against Iran also carries costs, the report said, Iran itself has estimated that sabotage to date has set back its centrifuge program by two full years.

The report suggested that the computer virus known as Stuxnet, which hit Iranian computers last year, was a joint effort by intelligence services in Israel and a European nation. That alleged effort involved a variety of governments besides Israel, involving equipment made to purposely malfunction after being tampered with before it physically entered Iran.

TIME noted that the resulting setbacks prompted Iran to announce it would manufacture all components of its nuclear program itself, but outside experts have been highly skeptical Tehran has the ability to actually do that.

“Iran has said for some time that they’re self-sufficient, but that’s a bag of wind,” Mark Fitzpatrick, a former State Department nuclear proliferation specialist told TIME.

Fitzpatrick noted that Iranian President Mahmoud Ahmedinejad announced in February that Iran had perfected a far more efficient centrifuge — a “fourth-generation” machine, three levels beyond its original centrifuges, made from designs purchased from Pakistan’s A.Q. Khan. He, however, said he doubts this is true.

“They haven’t been able to get the second generation to work over the last ten years,” noted Fitzpatrick.

Finally, the TIME report said, the alternative for Iran is importing equipment, but that leaves the product vulnerable to continued tampering, especially in the shadowy markets of front companies where Iran has been forced by U.S. and international sanctions to do much of its business.

“The easiest way to sabotage is to introduce faulty parts into the inventory from abroad,” Fitzpatrick said.